The present invention relates to en-route navigation guidance systems. These are systems that determine where a person on the move, such as an automobile (car) driver, is currently located and provide visual and/or auditory information to guide the person to a desired location. Such systems typically use signals from GPS satellites to determine the person's current location.
There are several types of en-route navigation guidance systems available to consumers today, as well as some proposed systems not yet implemented in commercial products. The user of such a system could be a driver of a motor vehicle, an operator of a boat, or a person traveling on foot, among others. We envision, however, that the invention will be particularly helpful for motor vehicle operators. The invention and its background are, therefore, described in that context without our intending to limit the invention to any particular navigation environment.
Among the more popular vehicle navigation systems in use at the present time are systems that employ voice commands, such as the OnStar® system available in the United States. Other types of the available vehicle navigation systems have a computer-like screen displaying a traditional map or a bird's eye view of the surrounding terrain, frequently in combination with voice commands. Other systems employ head-up displays presenting the driver with en-route guidance information that is reflected off the windshield and, to the driver's view, is superimposed over the terrain, or landscape, seen through the windshield by the driver within the driver's forward field of view.
There are problems with each of these types of systems.
Navigation voice commands for example, are found distracting, annoying or ambiguous by many people. Such distraction or annoyance can be the result of the fact that, when navigating a particular route, the primary attention of the driver's brain is necessarily focused on visual and not auditory reception. Such experiences create frustration, which may result in reluctance of some drivers to use voice command-based systems in their every-day driving. Such distraction during driving a motor vehicle can be dangerous. Some drivers attempt to clarify the ambiguities of voice commands by looking at a navigation screen, if available, while the vehicle is in motion, thus risking collisions. In addition, voice commands can interfere with the other sounds in the vehicle, such as music or a conversation with a passenger or over the phone. Navigation voice commands may also get in the way of voice recognition systems employed within the same voice range. For example a voice-operated cell phone may interpret the navigation voice commands as voice instructions for the cell phone.
Screen-based systems are inherently distracting. They require the driver to frequently look at the display and thus divert the driver's attention from the route ahead. They are not easy to use since they require constant correlation of the representation of the surrounding terrain, e.g. the map or the bird's eye view, with the actual surrounding terrain. This can be confusing and frustrating, particularly when the driver must choose from many similar and closely located alternatives, such as closely located driveways, complex intersections with intertwined traffic lanes, complex highway exits, and others. In addition, effective use of screen-based systems that display maps require good map reading skills, which many drivers do not have. A further problem with screen-based systems is that many people must put on reading glasses in order to read a navigation map display located in a dashboard of a motor vehicle. But such glasses cause the road ahead to appear blurry, causing risk of collisions.
Head-up-display-based systems usually display directional arrows or images of other two-dimensional navigation objects designed to convey en-route guidance information to the driver. Some such systems superimpose an image of the desired route over the real terrain, or display other objects. Systems displaying two-dimensional navigation objects, such as arrows or certain simplified maps, have some of the same drawbacks as the screen-based systems. In addition, one of the motivations for our invention is our recognition that it is undesirable for such images to be presented in a way that they appear in the driver's primary area of sight. By the “driver's primary area of sight” we mean a section of a three-dimensional space that encloses the visible road ahead of the vehicle, together with the all the visible objects that are on or relatively close to such road. We have realized that, at a minimum, such an image may be distracting or annoying to the driver. Moreover, objects presented in the driver's primary area of sight may obstruct real objects on the traveled path that the driver needs to pay attention to in the course of normal and safe driving. Such objects are, for example, other vehicles, pedestrians, traffic lights and road signs. Systems which use a combination of the navigation system types described above—for example by employing both the navigation screen and the navigation voice commands—compensate for each other's drawbacks to some degree, but introduce problems of their own. One problem, for example, is that the driver's attention may have to frequently switch between visual and auditory perception, which many people find distracting and/or annoying. And such combinations are more costly than any one individual system.
Our invention avoids or ameliorates many of the abovementioned shortcomings of prior art systems.